Traditional hip replacement surgery has been used in the United States since as early as the 1960's. The surgical technique to implant a hip has not drastically changed over the years, and today, this technique is quite successful. In fact, the surgical technique is prolifically used throughout the world and has a known success rate of over 90%. Certainly, the traditional surgical technique is fundamentally sound and predictable.
Unfortunately, traditional techniques to implant a hip have well recognized shortcomings. Most importantly, a rather large incision is made on the side of the hip. The incision can extend from 6 to 12 inches; the actual length of the incision depends on the size of the patient and type of surgery (revision versus total hip arthroplasty, for example). A long, deep incision can divide a number of important stabilizing muscles and tendons and further damage the hip joint and surrounding soft tissue. Inevitably, long incisions lead to larger blood losses, longer rehabilitation times for patients, and unsightly scar lines. A patient can easily spend four or five days in the hospital after a total hip arthroplasty, for example.
Recently, surgeons have been developing new, less invasive surgical techniques to perform total hip arthroplasty and revision hip surgery. Minimally invasive surgery, or MIS, is one such technique with great promise to become a popular and accepted technique for implanting a hip.
MIS has significant advantages over traditional hip replacement surgery. Most importantly, a rather small incision is made on the side on the hip. This incision is approximately 3 to 5 inches long, and the benefits of a shorter incision are enormous.
First and foremost, the patient can recover in a much shorter period of time after a MIS. The recuperation time in the hospital can be a few days and significantly reduce the cost to both the patient and hospital. In fact, some patients are leaving the hospital within 24 to 48 hours after the surgery. Obviously, this shortened time period is extremely important to the patient.
As another advantage, MIS is less invasive and traumatic to the patient. Significantly less soft tissue is disrupted in a minimally invasive surgery compared to a traditional hip surgery. Also, the amount of blood loss is reduced, and patients will require fewer blood transfusions. Further, the length of the scar is significantly smaller, and these scars are more cosmetically appealing. The incisions themselves heal in a much shorter period of time and are much less painful than a long ten or twelve inch incision. As such, the patient can sooner return to work or enjoy recreational activities. In short, the patient can more quickly return to a normal way of life.
Presently, instruments to perform MIS are being developed and refined. These instruments have a vital role in the ability to perform a successful minimally invasive surgery. These instruments, for example, must enable the surgeon to place the hip implant in a very precise location. If the implant is not accurately placed, then complications, such as dislocation or subluxation, can occur. Further and most importantly, the instruments must consistently and reliably perform through a small three inch opening in the patient.
A successful design of instruments for MIS has other challenges as well. Specifically, the instrument must be easy to use and facilitate the implantation procedure. If the MIS instrumentation is too cumbersome or not easy to manipulate, then the surgeon will be less likely to use minimally invasive surgery. The patient, then, will not reap the benefits MIS has to offer.
As yet another consideration, MIS instrumentation must appeal to a wide range of orthopedic surgeons with various skills and experience. If, for example, the instruments are too complex and complicated, then they will not be appealing and accepted in the orthopedic surgical community. Further yet, the training and skill level required to use the instruments and become proficient with them, cannot be overly taxing on the orthopedic surgeons.
While implanting or repairing a prosthetic femoral prosthesis in MIS for instance, measurements must be taken inside of the actual wound channel or surgical site. Accurate measurements are extremely important for properly sizing and fitting the femoral prosthesis into the intramedullary canal. During a traditional total hip arthroplasty or revision surgery, a ruler is used to make these measurements. These traditional rulers, though, are not shaped and sized to perform well in MIS. Specifically, the rulers are generally too long or too large to fit properly through the very small MIS incision. Additionally, the rulers are generally straight. If a straight ruler is positioned through an MIS incision, then the ruler itself or hand of the user can obstruct the line of site into the wound channel or surgical site. Further, it may be very difficult or even impossible to read the calibrated markings on the ruler since some measurements are taken at an angle inside the surgical site. Straight rulers simply will not work well in this situation.
A great advantage would be realized if a ruler were designed to make measurements inside the surgical site of MIS for hip replacement or reconstruction. Such a ruler would be shaped and sized to fit through the small MIS incision. Further, measurements could be taken without obstructing the line of sight into the surgical site. These measurements could be taken even if they were disposed at an angle in the surgical site. Other benefits as well would be realized from a ruler designed to be used with MIS.
In short, instruments, and in particular rulers for making measurements inside the surgical site, play a vital role in MIS surgery for hip implantation. It therefore would be advantageous to provide a new method and accompanying instrument for making measurements inside the surgical site in minimally invasive surgery.